Scientist at Work: Steven Chu; Master of Molecule Manipulation Works on the Wild Side

AN atom can be here, there and somewhere else all at once; it can be going both this way and that way; it can be rattling with internal energy and quiet. Such are the quirky freedoms of the quantum microworld that do not apply to automobiles, apples or people. But if there is an exception to this rule, it would be the mind of Dr. Steven Chu, the master of manipulating atoms and molecules who shared the most recent Nobel Prize in Physics with two other researchers.

Dr. Chu, a professor at Stanford University, ranges so widely among topics of interest to him that any attempt to keep up leaves a blurry succession of visual images, like a slide show inadequately describing one's dream vacation.

Here he is clutching a Reuben sandwich while filling a steno pad with sketches of an experiment to stretch DNA molecules like knotted rubber bands. Here, he is in the back of a cab where he is alternately shouting instructions to the driver and quietly rationalizing his mega-celebrity status in Taiwan. This one shows him explaining the cosmological theory of multiple universes to the Dalai Lama. And finally, here, in his lab, Dr. Chu is pointing through the window of a vacuum chamber to a hovering blob of atoms that are trapped and supercooled by the forces of laser light -- the achievement for which he won the 1997 Nobel Prize.

On a recent day in his Stanford office, the 50-year-old, aggressively trim Dr. Chu, wearing khaki trousers, a pullover shirt and scruffy tennis shoes, sat on a puffy couch and held court for his students and research associates. He bounced between taking phone calls and bantering about projects that combine conceptual simplicity with a faint air of unbelievability. In one experiment, the drop of a ''fountain'' of atoms is clocked to measure gravity so precisely that the technique could be used like a petroleum dowser to find hidden pockets of oil. In others, a single DNA molecule marked with fluorescent dyes is dragged about as a video camera mounted on a microscope captures the reptilian motions.

''I'm drawn towards the wilder, science-fiction-type stuff,'' said Dr. Chu, who grew up in Garden City, Long Island. ''It's much more fun for me to learn completely new things than it is to sort of ice the cake,'' he said. ''Well, that's part of the reason one is a scientist. It's not to just crawl into a little corner of some field and go to all of the meetings that all 50 of you in the world go to. 'Oh, this person twiddled that and look what happened.' After a while it becomes a little rococo, if you know what I mean.''

That adventurousness is reflected in Dr. Chu's recent moves from his original field of atomic physics into polymer science, chemistry and biology. But unlike the average scientific dilettante, Dr. Chu sees to it that this crosscutting work always bears the mark of his experimental dazzle and intuition for pay dirt. ''What Steve brings to science is an incredible technical virtuosity -- a sort of technical showmanship,'' said David Pritchard, a physicist at the Massachusetts Institute of Technology in Cambridge. ''There is this terrific scientific taste,'' added Daniel Kleppner, also of M.I.T. ''He has the vision to see new areas emerging. He's a damn good experimenter, but he's also highly creative.''

Those who work most closely with Dr. Chu say he also has the incalculably useful ability to see the complex interactions of the microworld directly, rather than relying on the equations that thicken the chapters of physics textbooks.

''He doesn't have to resort to those formulas,'' said Cheng Chin, one of Dr. Chu's doctoral students. ''He has atoms in his mind.''

Steven Chu emerged from a cauldron of academic overachievement. His father, who emigrated from mainland China to study chemical engineering at M.I.T., retired as a professor at Brooklyn Polytechnic University and is a member of the Academica Sinica, Taiwan's most distinguished scholarly society. His mother studied economics at M.I.T. and a prestigious university in China. Two brothers and four cousins eventually generated three M.D.'s, four Ph.D.'s and a law degree. And that doesn't count the aunts and uncles.

''I was to become the academic black sheep,'' Dr. Chu wrote in a biographical sketch for the Nobel Foundation. There is still an edge to his voice when he recalls that for years in his father's eyes, he never lived up to the dizzying scholarly achievements of his older brother, Gilbert Chu, an associate professor at Stanford School of Medicine.

With what he described as a ''relatively lackluster'' record at Garden City High, Dr. Chu was not accepted into Ivy League colleges. Instead, he attended the University of Rochester, where his intellectual appetite exploded, leading to undergraduate degrees in physics and math and a doctorate in physics at the University of California at Berkeley.

An encounter with the late Richard Feynman's ''Lectures in Physics,'' a comprehensive and idiosyncratic introduction to basic physics, ignited an interest in theoretical physics. Not until later, well into graduate school, did he start fiddling with equipment in physics laboratories at night. It was like Nat King Cole finding his voice: So long, jazz piano. ''I said, 'Well, it's ridiculous, sneaking in and making play experiments, and I'm ignoring my theoretical problem,' '' Dr. Chu explained. Experiments became the day job.

He quickly began a long-term relationship with the powerful light source called the laser. His method was to juice up the inadequate equipment he could buy off the shelf, which let him stay ahead of the beat scientifically. That improvisational approach served him well when he moved to the old AT&T Bell Laboratories, the famed center of technical and scientific innovation in New Jersey.

''He would come into my office with these great ideas, all excited, and scribble stuff up on my board,'' said Dr. Douglas Osheroff, who shared the previous Nobel Prize in Physics and is now a professor at Stanford. (The university has raked in five physics Nobels in the past 10 years.)

As to the cross-disciplinary flair Dr. Chu would develop, Dr. Osheroff said, ''that was a very standard approach at Bell Laboratories and almost part of the culture there.''

It was at Bell Labs that Dr. Chu met Arthur Ashkin, who was trapping microscopic particles with laser light and who dreamed of trapping atoms. Dr. Ashkin and his colleagues were the first to demonstrate that particles would ''stick'' to the laser beam for nearly the same reasons that dust sticks to a glass rod that has been charged positively by rubbing it with cat's fur. Even though a dust mote has no net charge, its negative charges -- electrons -- crowd over to the side closest to the rod, being pulled toward it like vacationers waving at the rails of a docking ship. That leaves a positive excess on the opposite side of the mote, but because the negative charges are closer to the rod, their attraction wins out and the mote sticks. In the Bell Labs apparatus, the dancing electric fields of laser light take the place of those static electrical charges, attracting a particle to the most intense parts of a laser beam. Instruments that move particles around with lasers have come to be called ''laser tweezers.''

After adding this technique to his repertoire, Dr. Chu expanded on it by ''gluing'' tiny polystyrene beads, which he could grab and move with laser tweezers, onto strands of fluorescent DNA. By stretching the DNA and dragging it through a soup of other DNA molecules, he and colleagues at Stanford later helped confirm theories developed by Pierre-Gilles de Gennes, the Nobel Prize winner at the Ecole Superieure de Physique et de Chimie Industrielles in Paris. Dr. de Gennes had predicted that any such long molecules, called polymers, should ''reptate,'' or change directions like a snake, whose entire body follows the same path without cutting corners.

''We've had theories of that kind of thing for years,'' said Bruno Zimm, a chemistry professor at the University of California, San Diego. ''Actually seeing it is something else.''

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Among other things, reptation helps explain the toy-store mystery of why Silly Putty bounces and squishes. If a child hurls it against a wall, the impact comes faster than the polymers in the putty can move along their tortuous paths, so the putty acts like a solid and bounces. But a slow squish gives the polymers time to slither around. Academics call such materials ''viscoelastic.''

Still more recently, using a different method for manipulating the polymers, Dr. Chu and his colleagues, Thomas Perkins and Douglas Smith, took virus DNA that was in a naturally coiled state and stretched it. They found that identical polymers beginning from the same state can uncoil in different ways, getting hung up in strange knots and bends -- behavior Dr. de Gennes called ''molecular individualism.''

This effect could be important in everything from the extrusion of plastics to the flow of oil in pipelines, where squirming, free-floating polymers reduce the drag when they are added to the oil -- improving the flow for reasons that are still poorly understood. And, noting that with every unraveling of the virus DNA polymers they used ''you have the same virus and the same genes and very, very different outcomes,'' he said with a laugh, ''So maybe you can take that as a moral in life -- that it's neither nature nor nurture.''

''Polymer physicists were goo-goo, ga-ga over it,'' Dr. Chu said of the DNA work.

But the loudest applause came when Dr. Chu used laser light to chill atoms, so that they -- like the beads -- could be trapped. At room temperature this would be a hopeless task, because atoms are moving at thousands of miles per hour.

In 1985, Dr. Chu and his colleagues at Bell Labs cooled a cloud of atoms to 240 millionths of a degree above absolute zero with what he called ''optical molasses.'' They did it by bathing the atoms in laser beams fired together from all directions, which created a kind of drag that slowed the atoms to inches per second, corresponding to the low temperature. That achievement finally allowed atoms to be laser-trapped.

''When I first heard about it, I said, 'That's incredible,' '' recalled Dr. Kleppner of M.I.T. ''And the next thing was, 'But of course; why not do that?' '' The molasses analogy was a brilliant way of seeing through the immense technical challenges posed by the optical cooler, he said.

Dr. Chu shared the Nobel Prize with William Phillips of the National Institute of Standards and Technology and Claude Cohen-Tannoudji of the Ecole Normale Superieure in Paris. All three have made enormous contributions to the science of atom cooling and trapping. The traps have become standard equipment for creating the ultraprecise timepieces called atomic clocks. The techniques are also often a starting point for outlandish physics experiments, such as when scientists at the University of Colorado, Boulder, created a new state of ultracold matter called a Bose-Einstein condensate two years ago.

Like a juggler whose hands become ever more difficult to follow over the years, Dr. Chu has continued playing tricks with trapped atoms. In one experiment, for example, he and Mark Kasevich of Yale University used laser pulses to put atoms into ''split personality'' states predicted by quantum theory. Both states feel the tug of gravity as they move on slightly different trajectories. The degree to which those states are compatible when the split atoms recombine gives a measure of gravity's strength to about a part in a billion. That is fine enough to detect underground geological features, like oil pockets.

Dr. Chu has also continued the push into biology, partly in collaboration with Jim Spudich, chairman of the biochemistry department at Stanford. This aspect of Dr. Chu's work has become so well known that he was almost lured away by another university's fetching offer to co-direct a new cross-disciplinary institute. ''I was tempted,'' he said.

He turned down the offer because of the difficult decisions the move would have entailed for his two sons, ages 13 and 16. Dr. Chu is divorced and shares in their care.

''Fundamentally, I'm happy here,'' he said in his office. ''I'm very much against people trying to leverage themselves and their institutions. I don't want to see academics go into a state of free agency.''

As high as his star has risen in the United States, it is nothing compared to his profile in Taiwan. His friend Yuan Lee -- yet another Nobel Prize-winning physicist -- now heads the Academica Sinica, of which Dr. Chu is a member. The combination of Dr. Chu's ties to Taiwan, his particular brand of charisma and a society that still lionizes scholars has led to hordes of cameras and reporters' shadowing him in public.

''One time he came back and said: 'Taiwan is crazy for me,' '' Mr. Chin recalled. A Taiwanese professor joked that Dr. Chu's popularity was second only to Leonardo diCaprio's for a time. ''DiCaprio is first by a whole lot,'' insisted Dr. Chu, who said that he speaks only basic Chinese with a heavy American accent.

Even the Dalai Lama found an opportunity to talk physics with him a few years ago. ''He was obsessed with finding out what physics could say about time,'' Dr. Chu said. ''I'm surmising why,'' he explained. ''If you're a Buddhist, you believe in reincarnation, and there's this conservation-of-souls problem,'' referring to the question of where new souls come from as the number of living beings in the world keeps expanding.

In his moments with the Dalai Lama, the exiled leader of Tibet, who wore his maroon and saffron robes for the public conversation, Dr. Chu outlined the speculative theory that the universe is just one of many that are appearing and disappearing like bubbles in a champagne glass. (The theory is notably championed by another Stanford physicist, Andrei Linde.) That way, as vast amounts of time passed and whole universes became inhospitable to life, souls might flit from one universe to another and keep the total number constant, Dr. Chu suggested.

The Dalai Lama's reaction?

''He just listened,'' said Dr. Chu. ''Juuuuust listened.''

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A version of this article appears in print on June 30, 1998, on Page F00001 of the National edition with the headline: Scientist at Work: Steven Chu; Master of Molecule Manipulation Works on the Wild Side. Order Reprints|Today's Paper|Subscribe